S&P 500 (SPX) Opens Up or Down on August 3?

Platform comparison

Market context

Polymarket is pricing this contract at **100% YES**, which means the market is treating an S&P 500 gap up at the open on 3 August as effectively certain on current information. On Polymarket, the position is settled in **USDC** and represented through **conditional tokens** on **Polygon**, so the price reflects demand for the “Up” token rather than a view on the index itself; the practical question is whether the official SPX opening print finishes above the prior session’s close.

The recent frame for that pricing is a strong Friday close and a firm overnight tone. The S&P 500 finished last week at **7,489.72** after rising **0.7%**, while SPX historical data show a **30 July close of 7,437.63** and a session open of **7,390.45**. Futures have also been pointing higher into the open, with reports of S&P 500 futures up around **0.5% to 0.6%** as oil prices fell and Middle East tensions eased, a combination that has supported broad risk sentiment[1][2][6][9][12].

For a trader, the key catalysts are the cash open itself and the scheduled macro data around it, especially the **ISM manufacturing index** release due at **10:00 a.m. ET**, which can move intraday equity sentiment after the opening print has already settled the market. News flow on Iran-related diplomacy and crude prices also matters because the latest rally has been tied to a drop in Brent and better risk appetite; the main dependency is whether futures strength holds through the bell rather than reversing on the first cash-hour volatility[1][9][12].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track S&P 500 (SPX) Opens Up or Down on August 3? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Alternative UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.